The uncontrolled flow of oil and/or gas from a subterranean well presents significant problems not only in terms of environmental contamination from the fluid issuing from the well, but also in terms of personal injury risks to those workers who undertake the responsibility to stem the uncontrolled fluid flow. In this connection, the fluid which issues from the well head is at extremely high velocities. If the uncontrolled flow of oil and/or gas is ignited, therefore, a relatively large area surrounding the burning well head becomes an inferno which compounds the problems associated with well head capping.
Equipment which are especially adapted to cap the uncontrolled flow of oil and/or gas issuing from a well head are known, for example, as evidenced by U.S. Pat. No. 4,192,376 (which utilizes the force of the fluid to responsively seat and engage a clamping device and then activate a valve mechanism), and U.S. Pat. No. 4,461,354 (which includes a hydraulically activated remote-controlled clamp which physically engages the exposed end of the pipe stem). These prior attempts, however, do not readily lend themselves to being removed quickly and transported to another well site for reuse (i.e., a need that was recently demonstrated by the mass destruction of Kuwait oil fields during the Persian Gulf War). It is therefore towards fulfilling such a need that the present invention is directed.
Broadly, the present invention resides in systems and methods whereby a well head can be prepared for capping and then capped so as to stem the uncontrolled flow of oil and/or gas therefrom. The invention contemplates the use of discrete shielded cutting and capping assemblies which can be maneuvered into place from a relatively safe distance (e.g., via a self-propelled mobile crane or the like) and then operated in a remote-controlled manner.
The cutting assembly is essentially comprised of an explosion proof shield. Once the cutting assembly has been maneuvered into position, the shield will bound a substantial portion of the well head thereby providing a measure of protection for workers involved in the casing cutting operation. A reciprocally acting wire cutting element may then be advanced into cutting contact with the well head casing. Continual incremental advancement of the cutting assembly will therefore sever the well head casing at a predetermined distance above the ground and thereby provide a casing stub which is then especially adapted to being acted upon by the capping assembly.
The capping assembly according to this invention may then be maneuvered into position after the cutting assembly has been removed from the well head site. The capping assembly has a cylindrical shield which completely bounds the cut well head casing and thereby provides a measure of protection for workers involved in the well head capping operation. A threading subassembly is removably attached below an internally threaded pipe fitting which, in turn, is subjacent to and supports a normally open valving mechanism. The threading subassembly is removably carried coaxially by a rotatable horizontally disposed drive ring which is capable of being controllably moved vertically relative to the well head casing.
Simultaneous rotation and controlled vertical displacement of the drive ring will cause the cutting assembly to form standard threads on the exterior surface of the well head casing. Continued rotation and vertical displacement of the drive ring will thereby cause the internal threads of the pipe fitting to engage the just formed threads on the exterior surface of the well casing (i.e., since the pipe fitting rigidly follows the motion of the threading subassembly). As soon as the pipe fitting engages a sufficient amount of threads on the exterior surface of the well casing, the rotation and vertical displacement of the drive ring is stopped. Subsequent closure of the remotely controlled valving mechanism supported by the pipe fitting will thereby stem the flow of oil and/or gas from the well head at which time the well head is capped. Once the well head is capped, the capping assembly can be relatively easily and quickly removed from the well site simply by disconnecting the threading subassembly from the pipe fitting and then lifting the capping assembly physically away from the now capped well head site.
Further aspects and advantages of the present invention will become more clear after careful consideration is given to the following detailed description of the preferred exemplary embodiments.